Update charted to 0.4.8 and roll

packages/watcher/lib/src/file_watcher.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library watcher.file_watcher;
-
 import 'dart:io';
 
-import 'watch_event.dart';
 import '../watcher.dart';
 import 'file_watcher/native.dart';
 import 'file_watcher/polling.dart';
 
 /// Watches a file and emits [WatchEvent]s when the file has changed.
 ///
 /// Note that since each watcher only watches a single file, it will only emit
 /// [ChangeType.MODIFY] events, except when the file is deleted at which point
 /// it will emit a single [ChangeType.REMOVE] event and then close the stream.
 ///
@@ skipping 14 matching lines @@
   factory FileWatcher(String file, {Duration pollingDelay}) {
     // [File.watch] doesn't work on Windows, but
     // [FileSystemEntity.isWatchSupported] is still true because directory
     // watching does work.
     if (FileSystemEntity.isWatchSupported && !Platform.isWindows) {
       return new NativeFileWatcher(file);
     }
     return new PollingFileWatcher(file, pollingDelay: pollingDelay);
   }
 }